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12V Lead Acid Battery Charging & discharging rate?

  1. May 30, 2012 #1
    Hi,

    I have simple question:

    In small OFF GRID wind turbine systems, it is worth to continuously charge & discharge 12V Lead Acid Batteries? this means that we want that our loads (lights, Fans e.t.c) are 24hours taking power from wind turbine & batteries will continuously charge & discharge 24 hours, so it is worth this type of system? or we first fully charge the batteries then we will discharge it? but the problem is we want our loads to run 24 hours from wind turbine.

    Please give reasons for answers or good references

    thanks
     
  2. jcsd
  3. May 30, 2012 #2
    Your precise question is hard to decipher. Sounds like you have continuous loads to be run from 12v lead acid [wet cell] batteries and are interested in how to keep the batteries charged most efficiently?

    Some insights: AGM batteries will charge over 15% more efficiently than wet cell lead acid batteries due to their low internal resistance; some 20% of wet cell lead acid power ends up heating the batteries instead of contibuting to the actual charging. AGM's cost more initially but will payback in terms of life cycle amp hours delivered per initial dollar.

    Use a smart charge controller [regulator]....they will most efficiently charge your batteries if the wind turbine has the energy to power it at maximum when called for. You need to choose a smart regulator than can be set to AGM or wet cell depending on your battery type. Don't bother considering gellcell batteries as they are less efficient and more expensive.

    Overall it would seem your most efficient charge strategy will be to charge the batteries whenever you can....when the wind stops you will have no options. The maximum charge rate for wet cell lead acid battery is about 20 or 25% of the amp hour rating; so for example, a wet cell battery with a 100 amp hour rating can be charged up to about 25 amps maximum. A smart charger will limit this for best battery protection. An AGM battery can be charged at its full amp hour rating; so a 100 amp hour AGM can be charged at 100.
    amps.

    Finally a smart regulator will prevent unnecessary trickle charging if loads are off. I have never found out why, but most batteries last longer when NOT continuously tricle charged according to manufacturers.
     
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